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0_Foo.sol

pragma solidity 0.5.10;

contract Foo {
    function bar() public {
        
    }
}

1_Storage.sol

pragma solidity 0.5.10;

contract Gateway {
    bool open;

    function accessCard() public {
        open = true;
    }
    
    function passthrough() public {
        open = false;
    }

    function getState() public view returns (bool) {
        return open;
    }
}

2_Maps.sol

pragma solidity 0.5.10;

contract StorageMaps {
    mapping (address => uint) storages;

    function set(uint x) public {
        storages[msg.sender] = x;
    }

    function getUserValue(address user) internal view returns (uint) {
        return storages[user];
    }
    
    function getMy() public view returns (uint) {
        return getUserValue(msg.sender);
    }
    
    function getFor(address user) public view returns (uint) {
        return getUserValue(user);
    }
}

3_Event.sol

pragma solidity 0.5.10;

contract DummyEvent {
 event Hooray();

 function () external {
   emit Hooray();
 }
}

4_SmartEvents.sol

pragma solidity 0.5.10;

contract DummyEvent {
 event SmartEvent(address indexed caller, uint256 value);

 function () payable external {
   emit SmartEvent(msg.sender, msg.value);
 }
}

5_Import.sol

pragma solidity 0.5.10;

import "https://github.com/OpenZeppelin/openzeppelin-solidity/contracts/token/ERC20/ERC20Mintable.sol";
import "https://github.com/OpenZeppelin/openzeppelin-solidity/contracts/token/ERC20/ERC20Detailed.sol";

contract Token is ERC20Mintable, ERC20Detailed {
    constructor() ERC20Detailed("Test Token", "TST", 18) public {}
}

6_Inheritance.sol

pragma solidity 0.5.10;

contract Parent {
 event ParentPick();

 function pickFromKindergarten() internal {
   emit ParentPick();
 }
}

contract Dad is Parent {
 event DadPick();

 function pickFromKindergarten() internal {
   emit DadPick();
   super.pickFromKindergarten();
 }
}

contract Mother is Parent {
 event MomPick();

 function pickFromKindergarten() internal {
   emit MomPick();
   super.pickFromKindergarten();
 }
}


contract Son is Mother, Dad {
 function goToHome() payable public {
   super.pickFromKindergarten();
 }
}